A goal from Sergio Aguero gave Argentina a 1-0 victory over defending champions Uruguay in Copa America Group B.
The striker netted in the second half to put Gerardo Martino's men on the brink of a place in the quarter-finals.
Argentina controlled most of the first half at the Estadio La Portada in La Serena - but they struggled to break down Uruguay's defence.
Uruguay, the most successful nation in the competition's history, were again without Luis Suarez, who is still serving an international ban after biting Giorgio Chiellini in last year's World Cup,
La Celeste went in at half-time - but they needed goalkeeper Fernando Muslera to produce a top-class save to keep out a header from Aguero midway through the first half.
However, the Argentina striker was not to be denied 11 minutes into the second half, when he made the right connection with a diving header following a long ball from his Manchester City team-mate Pablo Zabaleta.
Lionel Messi came close to doubling the lead in the 83rd minute but his low shot was saved by Muslera.
Argentina had goalkeeper Sergio Romero to thank for preserving the three points - he made a superb low save to deny Uruguay striker Abel Hernandez a 90th-minute equaliser.
And the visitors' last chance went soon after when defender Diego Godin headed Carlos Sanchez's cross over the bar.
Zabaleta told Television Publica afterwards: "The clashes against Uruguay are always the same, tough battles.
"We wanted to exploit spaces out wide and the goal came from there. We defended well when it was needed and were much more balanced than the game against Paraguay."
Argentina top the group with four points alongside Paraguay following the 2-2 draw between the teams in their opening match. La Celeste are a point behind and Jamaica bottom after two defeats.
Source: PA
